[Answer] The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. A.had chloroplasts B.used hydrogen sulfide as an energy source C.used water as an electron source for photosynthesis D.were chemoautotrophic E.were oxygen respiring

Answer: A

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The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. A.had chloroplasts B.used hydrogen sulfide as an energy source C.used water as an electron source for photosynthesis D.were chemoautotrophic E.were oxygen respiring The atmosphere of early Earth probably contained no O2 until the emergence of organisms that. used water as an electron source for photosynthesis . How does continental drift affect living organisms . The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. A.had chloroplasts B.used hydrogen sulfide as an energy source C.used water as an electron source for photosynthesis D.were chemoautotrophic E.were oxygen respiring The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. A. used water as an electron source for photosy...

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